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Detection rules › Kusto

Cloudflare - Unexpected URI

Status
available
Severity
medium
Time window
1h
Source
github.com/Azure/Azure-Sentinel

'Detects client requests to unusual URI.'

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1133 External Remote Services, T1190 Exploit Public-Facing Application

Rule body kusto

id: dcb797cd-a4cd-4306-897b-7991f71d7e28
name: Cloudflare - Unexpected URI
description: |
  'Detects client requests to unusual URI.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: CloudflareDataConnector
    dataTypes:
      - Cloudflare
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1190
  - T1133
query: |
  Cloudflare
  | where HttpRequestMethod =~ 'GET'
  | where DstBytes != 0 or SrcBytes != 0
  | where ClientRequestURI matches regex @'(127\.\d{1,3}\.\d{1,3}\.\d{1,3})|(10\.\d{1,3}\.\d{1,3}\.\d{1,3})|(172\.1[6-9]\.\d{1,3}\.\d{1,3})|(172\.2[0-9]\.\d{1,3}\.\d{1,3})|(172\.3[0-1]\.\d{1,3}\.\d{1,3})|(192\.168\.\d{1,3}\.\d{1,3})'
entityMappings:
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SrcIpAddr
version: 1.0.1
kind: Scheduled

Stages and Predicates

Stage 1: source

Cloudflare

Stage 2: where

| where HttpRequestMethod =~ 'GET'

Stage 3: where

| where DstBytes != 0 or SrcBytes != 0

Stage 4: where

| where ClientRequestURI matches regex @'(127\.\d{1,3}\.\d{1,3}\.\d{1,3})|(10\.\d{1,3}\.\d{1,3}\.\d{1,3})|(172\.1[6-9]\.\d{1,3}\.\d{1,3})|(172\.2[0-9]\.\d{1,3}\.\d{1,3})|(172\.3[0-1]\.\d{1,3}\.\d{1,3})|(192\.168\.\d{1,3}\.\d{1,3})'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
ClientRequestURIregex_match
    • (127.\d{1,3}.\d{1,3}.\d{1,3})
    • (10.\d{1,3}.\d{1,3}.\d{1,3})
    • (172.1[6-9].\d{1,3}.\d{1,3})
    • (172.2[0-9].\d{1,3}.\d{1,3})
    • (172.3[0-1].\d{1,3}.\d{1,3})
    • (192.168.\d{1,3}.\d{1,3})
DstBytesne
  • 0 transforms: cased
HttpRequestMethodeq
  • GET
SrcBytesne
  • 0 transforms: cased